Recently, the 3D printing, also known as the additive manufacturing (or called “AM”), is more and more general, among which the fused deposition modeling (hereinafter “FDM”) additive manufacturing is widely applied to kinds of machines. The FDM additive manufacturing is applying a three-axial machine cooperating with a nozzle to extrude plastic materials or other materials for molding. The extrusion nozzles generally comprises a ratchet for holding wire-shaped materials, and the wire-shaped materials are push to the nozzles by friction and are heated to a specific temperature for fusing the wire-shaped materials to the molten state at the ends of the nozzles. Fine wire-shaped materials are extruded through the tiny nozzles, then filled to the working area in layers, and stacked for molding.
The materials used by the FDM additive manufacturing are mostly the wire-shaped thermofusible materials. Since the thermofusible materials themselves have certain shrinkage ratios, the sizes and the quality of molding are further affected. Therefore, in order to enhance the printing quality, the temperature of the molding space should be lower than the heat distortion temperature of the thermofusible materials.
However, since the extrusion nozzles of FDM additive manufacturing are heated to a specific temperature to make the thermofusible materials fuse to the molten state, if the temperature of the molding space is lower than the heat distortion temperature of the thermofusible materials, then the temperature adjacent to the nozzles is approaching the heat distortion temperature of the thermofusible materials. Consequently, the thermofusible materials are easy to be softened, which makes the strength of the thermofusible materials be decreased. The friction between the ratchet and the thermofusible materials is also changed, such that the materials cannot be extruded smoothly, and the quality of printing is further lowered.
In prior arts, the temperature is decreased by air flow through disposing fans adjacent to the ratchet. However, since the temperature adjacent to the nozzles is already close to the heat distortion temperature of the materials, the cooling effect of using air inside the extrusion nozzle to operate convection are limited. In addition, when the fans rotate, the extrusion nozzles are easy to vibrate, which makes the printing operations unstable and affect the printing quality.
Therefore, there is a need of providing an extrusion device of a three-dimensional printer and a cooling mechanism and a cooling method thereof to solve the drawbacks in prior arts, solve the questions of decreasing the temperature of thermofusible materials, and achieve the advantage of enhancing the cooling effect and the printing quality.